<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Document</title>
  <style>
    div {
      height: 500px;
    }

    .aside {
      width: 300px;
      float: left;
      background: yellow;
      height: 600px;
    }

    .main {

      background: aqua;
      margin-left: 200px;
    }
  </style>
</head>
<body>
<div class="aside"></div>
<div class="main"></div>
</body>
</html>

